Band Alignment at the Al2O3/β-Ga2O3 Interface with CHF3 Treatment*

Abstract

The energy band alignment at the atomic layer deposited Al2O3/β-Ga2O3 interface with CHF3 treatment was characterized by x-ray photoelectron spectroscopy and secondary ion mass spectrometry (SIMS). With additional CHF3 plasma treatment, the conduction band offset increases from 1.95±0.1 eV to 2.32±0.1 eV; and the valence band offset decreases from 0.21±0.1 eV to −0.16±0.1 eV. As a result, the energy band alignment changes from type I to type II. This energy band alignment transition could be attributed to the downshift of the core-level of Ga 3d, resulting from the Ga–F bond formation in the F-rich interfacial layer, which is confirmed by the SIMS results.